278 MORPHOLOGS AND EVOLUTION
skulls of Kant, Gau?s and Dirichlet showed marked development of the parietal region. In the skulls of Bach and of Beethoven, which have been studied by His and by Flechsig. there was a marked development of the posterior regions of the brain ^parieto-occipito-temporal) and of the Rolandic region, while the prefrontal lobes were of only comparatively insignificant proportions. The brain of the astronomer Gylden, examined by Retzius, showed considerable development of the parietal lobe, especially of the angular gyrus. In Helmholtz's brain, according to Hansemann, the precuneus and parietal region included between the angular gyrus and the upper temporal gyrus were remarkable in size. Raffaelle's cranium, studied by llingazzini in an authentic chalk drawing at Urbino, shows a striking contrast between the modest height of the forehead and the great expansion of the occipital and parietal lobes. The skulls of Gauss and Richard Wagner, according to His and Flechsig, on the contrary exhibit a striking development not only of the posterior association area, but also of the anterior or prefrontal association area of Flechsig."
In all the Apes each cerebral hemisphere is divided into the same lobes as in Man—frontal, parietal, occipital, temporal and central ^island of Seil). The cerebrum does not conceal the cerebellum so completely.
The frontal and parietal lobes are separated by the central sulcus, which is the boundary between the precentral and postcentral gyri. In the former are situated most of the motor centres. Our knowledge of the localization of the motor centres is due to the observations of Beevor and Horsley (229) on the Orang, and